The widespread use of computers has led to the creation of networks of various kinds to facilitate the exchange of data between computers and the cost-effective use of sharable resources such as printers and file servers.
One common kind of network is the so-called Local Area Network (LAN), typically used for connecting personal computers and computer workstations to each other and to sharable resources. A LAN often has multiple `segments`, each segment being a section of network which is separated from all other sections by one or more devices (such as bridges or routers) for filtering messages traversing the network. LANs have grown to the extent that some are very complex, comprising tens or hundreds of segments with hundreds or thousands of devices coupled to them.
A segment in the context of a LAN is an example of a notional subdivision of a network the equivalent of which in the context of other kinds of network may be referred to as a `domain`. National and international telecommunications transmission networks for carrying voice and data signals are increasingly being designed around the use of computers. In particular, a second, computerized, signalling network is frequently provided in parallel with, and for controlling switching and other operation of, the transmission network carrying voice and data traffic. This signalling network may operate in accordance with, for example, an agreed standard commonly known as Signalling System No. 7 (SS7). An entire SS7 network may have many thousands of signalling points interconnected by a large number of signalling links. Such a network is typically treated as comprising several sub-divisions known as domains. A domain may be any subset of the overall network which it is convenient to identify as a distinct entity for commercial or operational reasons.
The term domain is used herein to refer to any convenient sub-division of a network, such as a segment in a LAN or a domain in an SS7 network.
Large networks present formidable problems of management and maintenance. A fault in one device on the network can cause undesirable effects over extensive portions of the network, without the identity of the source of the problems being immediately evident.
With a view to assisting fault-finding and repair, various measurements are typically made of a variety of operating parameters of each domain of a network, such as (in the case of a LAN) cyclic-redundancy check (CRC) errors, data frame or packet communication rates and utilization. However, on a large network the sheer quantity of such measurements is a significant hindrance to their effective use in fault-location. There may be several hundred such measurements in total, of which just one may be the key to the true cause of a problem. None of the other measurements will necessarily provide any indication of the identity of that key measurement. Thus successful identification of the key measurement is entirely haphazard, relying on chance or an exhaustive and time-consuming review of every available measurement. Furthermore, there has previously been no effective way of presenting a summary of such measurements which can alert a network manager to a condition which may be indicative of a fault and which warrants investigation.
It is an object of this invention to provide a method and apparatus for monitoring the status of systems in which many measurements are made of multiple parameters (and of which a multiple domain data communication network is one example), which at least alleviate these problems.
A technique has been proposed in U.S. Pat. No. 4,527,240, for the unrelated field of blood chemistry evaluation, in which the values of various measured parameters of only one blood sample are plotted on respective radial axes on a circular coordinate arrangement. However, this proposal relates to a completely different technical field from the present invention, and moreover does not even address the problem of identification of a key measurement among a very large population of measurements obtained from a multiplicity of sources.